Diseases of Sweet Cherry Trees


The sweet cherry tree, Prunus avium, requires well-drained soil and does not tolerate excessive pruning. Mature sweet cherry trees grow up to 30 feet tall; there are no dwarf varieties. The trees are attractive to birds and the fruit should be protected with netting. Cherry trees require little maintenance for fruit production as long as disease prevention practices are followed.

Fungal Diseases

Black knot is a common fungal disease of cherry trees throughout North America. The infection produces abnormal growths on the bark and light brown swelling. White patches on new leaves indicate an infection of the powdery mildew fungus. Leaves will eventually curl and fall from the tree. Cherry leaf spot is common in humid environments and results in dark spots on the leaves. Some leaves may turn yellow; others develop white spots on the underside. Brown rot is an that causes the fruit to rot quickly. Young branches, blossoms and fruit become infected with the fungus, which produces gray-brown spore bunches.

Fungal Treatment

Fungicide application, in addition to pruning infected areas, is the best treatment for black knot. Black knot will kill the tree within two years if no treatment is applied. Treat powdery mildew with fungicide and by pruning infected branches and leaves. Rake and destroy foliage affected by cherry leaf spot. Apply fungicide for control. Control brown rot by removing and destroying shrunken fruit and infected branches. Destroy all rotted fruit that has fallen. Spray the tree with fungicide specific for brown rot three weeks prior to the fruit ripening.

Bacterial Diseases

Canker is a disease caused by two forms of bacteria. Spots form on the leaves similar to leaf spot, with the addition of cankers on the trunk and branches. Bacterial canker is also referred to as dead bud, as the first sign of the disease is dead buds in the spring. Crown gall produces a gall (ball formation) on the main stem and branches of the tree. Young galls are soft and tan with a frosty appearance. Older galls become hard and black.

Bacterial Treatment

Prune canker-infected branches in late winter and destroy them. Disinfect pruning equipment--leaf spot bacteria will transfer on the cutting blades. Treat canker infections with a fungicide that contains copper sulfite. Apply it in the fall. Young tree stock with crown gall is treated by destroying the tree. Treat mature trees by applying Gallex to the gall formation.


Prevention includes following proper planting requirements for the tree. Plant standard-sized trees at least 30 feet apart to maintain air circulation. Prune to open the tree head and remove dead branches. Fertilize at least once a year to keep the tree healthy.

Keywords: cherry disease, cherry fungus, sweet cherry care

About this Author

Jennifer Loucks has been writing since 1998. She previously worked as a technical writer for a software development company, creating software documentation, help documents and training curriculum. She now writes hobby-based articles on cooking, gardening, sewing and running. Loucks also trains for full marathons, half-marathons and shorter distance running. She holds a Bachelor of Science in animal science and business from University of Wisconsin-River Falls.